1. Field of the Invention
The present invention relates to a display device comprising a self light-emitting display.
2. Description of the Related Art
As shown in FIG. 1, a self light-emitting display 10 is known in which data electrodes and scanning electrodes are arranged in matrix form, and a modulating voltage is applied by a data driver 11 to the data electrode side while a threshold voltage is applied by an operation driver 12 to the scanning electrode side. The display 10 as thus configured is called a passive display.
FIG. 2 shows a light-emitting characteristic of a self light-emitting element for use in the self light-emitting display.
As shown in FIG. 2, the self light-emitting element starts emitting light upon application of a voltage not lower than a light-emission starting voltage “Vstart”. The light-emitting luminance increases as the voltage applied to the self light-emitting element becomes higher.
In a display device comprising the above-mentioned self light-emitting display, for example, a threshold voltage “Vth” corresponding to the light-emission starting voltage “Vstart” is sequentially applied to each scanning electrode of the self light-emitting display, as shown in FIG. 3. A modulating voltage “Vmod” of 0 to Vmodmax, according to the signal level, is applied to the data electrodes of the self light-emitting display. As a result, a voltage of “Vth+Vmod(0≦Vmod≦Vmodmax)” is applied to a light-emitting element which is an intersection of the scanning electrode and the data electrode, and light is emitted at a luminance based upon the applied voltage.
In such a conventional display device (first conventional example), there is a problem in that “Vmodmax” cannot be set sufficiently large due to performance of the data driver 11 and thereby high luminance cannot be obtained.
For obtaining high luminance, a display device (second conventional example) has already been developed in which “Vth” is set higher than the light-emission starting voltage “Vstart”, as shown in FIG. 4. In the second conventional example, however, there is a problem in that the light-emitting element emits light in some quantity even with the signal level set to 0 (the modulating voltage “Vmod” set to 0), thereby leading to degradation in contrast.